Endurance Electrolyte Replacement Calculator
Dial in sodium, potassium, and magnesium targets for long endurance sessions. Enter your sweat rate, lab-tested or estimated mineral losses per litre, and planned duration to see hourly and total replacement goals.
CalcSimpler Examples
- 1.0 L/h sweat, 900 mg Na, 200 mg K, 40 mg Mg losses over 3 h ⇒ Per hour: 900 mg Na, 200 mg K, 40 mg Mg | Total: 2700 mg Na, 600 mg K, 120 mg Mg
- 1.3 L/h sweat, 1100 mg Na, 250 mg K, 50 mg Mg losses over 5 h ⇒ Per hour: 1430 mg Na, 325 mg K, 65 mg Mg | Total: 7150 mg Na, 1625 mg K, 325 mg Mg
FAQ
Where do the mineral loss numbers come from?
Use lab sweat testing results or reputable charts that estimate sodium, potassium, and magnesium loss per litre.
How precise are the recommendations?
They provide a starting point; adjust for gut tolerance, weather, and product labels during training.
Do I need to replace 100% of losses?
Not always. Many athletes target 60–80% of sodium losses and supplement potassium and magnesium as tolerated.
Additional Information
- Sodium drives fluid retention, while potassium and magnesium support muscle contraction and nerve signalling.
- Sweat rate can be estimated by weighing yourself before and after training without fluid intake.
- Combine electrolyte intake with adequate fluids and carbohydrates for long endurance events.
CalcSimpler